const Koa = require('koa');
const app = new Koa();
// 注册中间件1
app.use((ctx,next) => {
    console.log(1)
    next()
    console.log(4)
})

app.use((ctx,next) => {
    console.log(2)
    next()
    console.log(3)
})
app.listen(80)